A known support structure of the steering column tube in a vehicle such as the automobile is such that the steering column tube is retained by the column support bracket, and the column support bracket is mounted to the support member such as the vehicular body by bolts. It is known in the art that the column support bracket is made of such a material and shape as permitting plastical deformation so as to absorb an impact energy applied through a steering wheel to the steering column tube. Such a technical idea is disclosed in Japanese Utility Model Laid-open No. 59-1668.
In a conventional support structure of an energy absorbing type steering column tube, a retainer portion of the column support bracket for inserting the steering colunn tube into a retainer hold and fixedly mounting same thereto is integrally connected through a bent portion to a support portion provided on a lower side of the steering column tube. When an external force is axially applied through the steering wheel to the steering column tube, the bent portion is plastically deformed to absorb the impact energy.
However, in the above-mentioned support structure, since the bent portion is provided at only one position on the lower side of the steering column tube, that is, at a single side position of the steering column tube, satisfactory plastical deformation may not be obtained against the external forces applied to the steering column tube in various directions, and accordingly energy absorbing action may not be sufficiently effected.
The external force is sometimes applied to the steering column tube in such a direction at a predetermined angle with respect to an axis of the steering column tube. Especially, when the external force is applied from the direction where the bent portion of the column support bracket is located, that is, the external force is applied from the lower side of the steering column tube, the bent portion is satisfactorily plastically deformed to effect the energy absorbing action. When the external force is applied to the steering column tube from the same direction as the axis of the steering column tube, the bent portion is satisfactorily plastically deformed in the same manner to effect the energy absorbing action. However, when the external force is applied from the direction where the bent portion is not located, that is, the external force is applied from the upper side of the steering column tube, a compression load is applied to the bent portion to render the plastic deformation of the bent portion unsatisfactory, which results in insufficient energy absorbing action.
Further, since the bent portion for absorbing the impact energy is provided on the lower side of the steering column tube, the support portion of the column support bracket is required to be shaped such that is surrounds the steering column tube. As a result, the shape of the bent portion is rendered complicated, and manufacture of the same is also difficult.
Further, the bolts to be mounted to the column support bracket are located on both sides to the steering column tube at a position opposed to a driver's knee, and the bolts are projected from the column support bracket. As a result, when the driver moves his foot in operation of a pedal, the knee abuts against the projected bolts to generate to the driver an uncomfortable feeling.
To solve this problem, various measures have been proposed, and one of such measures is that the bolts are mounted at a position not opposed to the position of the driver's knee. However, according to this measure, a supporting method of the steering column tube must be changed, and arrangement of parts in a small space inside of an instrument panel which is usually a support member of the steering column tube must be also changed. As a result, change in designing or productive technique must be accompanied.
To cope with this problem, a protector for covering a projecting portion of the bolt is provided without changing the mounting position of the bolt, so that the knee may not directly abut against the bolt. However, as the protector is formed independently of the column support bracket, the number of parts is increased, and a specific structure for mounting the protector is needed so as to thereby render the same complicated and in design having an increased cost. In a particular case where the protector is mounted by a bolt, the bolt is required to be located at a position not opposed to the position of the knee.
Accordingly, it is an object of the present invention to provide a column support bracket of a simple shape which may effect sufficient energy absorbing action with respect to various dimensional external forces applied to the steering column tube.
It is another object of the present invention to eliminate a problem in mounting of a protector for covering a bolt if the protector is used.